1. Technical Field of the Invention
The present invention relates to a recordable optical disk recording method and a recordable optical disk apparatus to record new data on a recordable optical disk of rewritable type by adjusting recording conditions based on original recording conditions of another recording apparatus which has recorded old data on the optical disk.
2. Prior Art
Recordable optical disks are available as write-once-read-many optical disks such as CD-R, DVD-R, DVD+R and as rewritable optical disks such as CD-RW, DVD-RW, DVD+RW, and DVD-RAM. Recording characteristics vary with manufacturers and even recordable optical disk types of the same manufacturer. When recording data on a recordable optical disk, the optical disk recording apparatus normally detects identification information (disk ID) recorded on the optical disk. The optical disk recording apparatus performs OPC (optimum power control) to determine an optimum write power for the object disk. The optical disk recording apparatus adjusts the recording conditions for attaining optimal recording quality, and then writes data by the determined optimal write power of the laser beam (e.g., see patent document 1).
Patent document 1 is Japan Patent Application Laid-Open No. 11-7645 (pp. 5-7, FIGS. 5 and 6).
However, the optical disk apparatus described in Patent document 1 may degrade jitter characteristics of reproduced data and may increase an error rate of the reproduced data in case that the optical disk apparatus overwrite the data on a recordable optical disk on which another optical disk apparatus has already recorded old data.
Generally, optical disk recording apparatuses use different recording conditions depending on manufacturers and models of the apparatuses. Nonetheless, the conventional optical disk apparatus described in Patent document 1 only memorizes its own recorder identification information in correspondence to disk identification information which identifies types or models of recordable optical disks. Therefore, when a second optical disk recording apparatus overwrites data on a recordable optical disk on which a first optical disk recording apparatus has recorded data, the OPC is indispensable for finding an optimum write power value for the second optical disk recording apparatus. Even if the data is recorded after finding the optimum power value based on the OPC, however, the recording condition of the second optical disk recording apparatus differs from that of the first optical disk recording apparatus that recorded the original data. Consequently, the original data may not be completely erased by the second optical disk recording apparatus prior to the writing of new data over the original data.
Generally, the optical disk recording apparatus tunes the write power and erase power of the laser beam to form pits with the same width (shape) and to completely erase the original data during overwriting. However, when the recording rate of data varies, the formed pits may have different widths (shapes) due to deviations in the laser diode or rewritable optical disk materials. When overwriting data by forming a new pit, the new pit may not be able to completely erase a previously formed pit due to such difference of the pit width. When data is recorded at 4× speed on the rewritable optical disk, for example, overwriting pit formed at 1× speed cannot completely erase the old pit recorded at 4× speed on the same rewritable optical disk. This may degrade jitter characteristics of the data reproduction and increase the error rate.
The conventional optical disk recording apparatus uses different recording conditions such as the write power, the erase power, the bottom power, the write strategy, and the spot shape depending on manufacturers, models, firmware versions, and recording rates. Further, the rewritable optical disk is subject to different recording characteristics depending on recording conditions. When a first optical disk recording apparatus is used to record data on the rewritable optical disk, overwriting data using a second optical disk recording apparatus degrades jitter characteristics and increases the error rate. This is because a previous pit formed by the first recording apparatus on the rewritable optical disk cannot be erased completely by the second recording apparatus. Stated otherwise, a new pit cannot be formed by the second recording apparatus so as to completely cover the original pit formed by the first recording apparatus.